<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>

    /**
     * db
     */
    console.log(window.alert)
    function foo() {
        console.log('你好')
    }
    console.log(foo)
    if(foo){
        alert('a')
    } else {
        alert('b');
    }
</script>
</body>
</html>